Facsimile recorder



Feb. 1,"1944 RECEIVER W. G. H, Fl-NCH FACSIMILE RECORDER Filed July 31,1937 III' INVENTOR.

William finch BY 2 Z Z ATTORNEY.

Patented Feb. 1, 1944 uni-TED STATES PATENT OFFICE FACSIMILE RECORDER-William G. H. Finch, Newtown, Conn., assignor to FinchTelecommunications, Inc., Passaic, N. J a corporation of DelawareApplication July 31, 1937, Serial No. 156,625

(c1.1vs

3 Claims.

my co-pending application Serial No. 123,770,

filed February 3, 1937, now Patent No. 2,203,461,

granted June 4, 1940. The signals are transmitted as a modulated carrierwave having a fundamental frequency preferably in the range of twothousand cycles per second. The method of transmitting and receiving thepicture are optemplate employing electro-static recording to increasethe recording speed and quality of the reproduction. In a preferredembodiment I employ a carbon content paper coated with a mercury oxidefilm and break down the film in accordance with the received picturesignals impressed thereon at a high voltage in a novel manner to obtaina reproduction which has shading variations corresponding to the varyingpicture signal intensities.

I have discovered "that by connecting a carbon content record sheet tothe positive side of the picturesignals and connecting the moving stylusto the negative side thereof that the film of carbon particles releasedfrom the surface of the sheet during the electrostatic breakdown actionthereof will not be collected at the stylus and thereby avoidingsmudging of the reproduction.

It .is among the objects of my present inven-- tion to providesimplified recording apparatus for particular use in facsimile receiversto be used by laymen in the home so as to require a minimum "of skilland attention to obtain results of high quality; to provide a novel highspeed continuous sheet facsimile'recording system employingelectrostatic breakdown of a film on a sheet to render a contrastingimage with respect to the color of the sheet and thereby make visiblethe picture to be reproduced; and to provide improved and simplifiedrectifier connections to the electrostatic breakdown electrode toprevent smudging of the picture.

These and further objects of my present in-' vention will becomeapparent in the following description in connection with the drawing, in

which:

Figure 1 is a schematic electrical diagram of a preferred arrangementfor carrying out my in vention and Figure 2 is an arrangement formounting the record sheet in the recorder unit.

The picture signals are preferably generated by a facsimile transmittersystem as disclosed in tional and may be over land, wire or radio. Forgeneral application of the present system as a home-facsimile recorder,the radio broadcasting of the signals is employed. I v

The receiver i0 is responsive to the channel over which the modulatedaudio frequency car rier picture signals are transmitted. These signalsare delivered to the push-pull transformer H as an audio frequencycarrier current modulated by the picture signals. The secondary of thetransformer H is connected to the push-pull tetrode amplifier stagel2--l2 through a potentiometer arrangement H for varying the output ofthe signals from the amplifier [2. The biasing resistor I4 is connectedin series between the cathodes of the amplifier stage l2 and ground toprovide suitable biasing potential for the amplifier stage. The anodesof the push-pull amplifier stage are connected to the primary of theoutput transformer l5. Suitable potential is applied to the anodes andscreen grid electrodes of the push-pull. amplifier stage l2 asindicated.

The audiofrequency output from the pushpull transformer i5 is rectifiedby the double rectifier tube 86, the anodes I1 and I8 of which areconnected to the outer terminals of the secondary of the transformer Hi.The output of the rectification stage existing at the terminals 20 and2l consists of a varying uni-potential signal. Terminal 2!! connected tothe center tap of the secondary of the transformer I5 is the negativepotential; the terminal 2! connected to the cathode of the rectifier I6is positive as will be understood by those skilled in the art.

The record sheet 23 is mounted in a roll 24 and is advanced past theoscillating stylus 25 line by line in accordance with the oscillation ofthe scanner system. A preferred manner for advancing the record sheetline by line and the structure for mounting the record'sheet isdescribed in the Patent No. 2,109,109 referred to above. The recis heldagainst the block 26 by a fiat spring 21,

as described in the co-pendin-g application referred to. The stylus 25comprises a metallic pin which is mounted at the end of a scanner rod28.

The rod 28 is secured at the end 30 of the vertically oscillated rod 3|by means of a set screw 32. The rod 28 is adjusted in a slot in the post3|] to maintain the point of the stylus 25 in a light contactingarrangement with the surface of the sheet 23. A spring 33 is preferablyinserted between the post 30 and a collar 34 attached to the rod 28 nearthe stylus 25 so as to facilitate in the adjustment of the position ofthe stylus 25.

A source of mechanical power, such as an electric motor driven at apredetermined speed (not shown) is connected to a shaft 35 coupled tothe driven shaft 36 of the scanner system through an overrunningclutch-37. The driven shaft 36 oscillates the vertical scanner shaft 3|in a predetermined manner through the schematically indicated mechanismat 38. A preferred mechanism for performing the oscillation of the scanner shaft 3| from a continuously driven shaft by means of mechanismlocated at 38 is also illustrated and described in detail in my PatentNo. 2,109,109. The oscillation of shaft 3| causes the stylus 25 to movein the arc (defined by the radial dotted lines 3939 as shown in Figure2) across the record sheet 23. It is to be understood that the recordsheet 23 is advanced by a distance equal to the width of the scanningline once per oscillation of the stylus 25.

The record sheet 23 of my present invention preferably consists of apaper having a high carbon content to render it conductive and having athin film of mercury oxide coated on the sensitive surface, namely, thesurface contacting the stylus 25. A voltage applied between the stylus25 and the metallic block 26 contacting the opposite side of the papercauses an electrostatic breakdown through the paper. The portion of therecord sheet across which the discharge takes place is rendered visible.In the present case, the mercury oxide film is orange in color, coveringthe dense black paper. When breakdown occurs, the black paper is visiblethrough the orange coating as a black line. The degree of the marking onthe paper is determined by the magnitude of the voltage and, therefore,the relative shading of the picture being transmitted is reproduced as ablack-white half-tone effect on the record sheet.

The rectified picture signals are connected to the scanning system inthe following manner:

The negative terminal 20 is connected to the stylus25 through the camswitch 40 when the switch is connected to the contact 4|. The cam switchcontact 4| is connected to the metallic post 30 through a pigtail lead42. The post 3|] is conductively connected to the metal stylus 25through the rod 28, The post 30 is insulated from the verticallyoscillated shaft'3l and the driving system by means of an insulationpiece 43, which mechanically connects the post 30 upon the rod 3|. Thepositive terminal. 2| from the rectified picture signal output isconnected directly to the metal block 26 which contacts the,

actuating of the cam switch a described in my Patent No. 2,109,109 andto its actuation in the synchronizing system described in my Patent No.2,069,061 which issued on January 26, 1937.

Energization of the sync ronizing magnet 46 during reception of the snchronizing impulses attracts lever 48 away from the periphery oi theoverrunning clutch 31 and prevents it from disengaging the clutch 31.The notch 49 in the surface of the stop plate of the overrunnlng clutch31 would normally engage with the projection at the end of .lever 48 todisengage the clutch 3! and thereby stop the scanner movement. Thesynchronizing impulse causing energization of the magnet 46 raises thelever 48 and prevents the disengagement of the clutch 31 if the receiveris in proper synchronous and phase relat1on with the transmitter. Thissynchronizing action is also described in detail in the referencesreferred to disclosing details of the synchronizing mechanism.

An important feature of my present invention resides in the connectionof the carbon sheet proper to the metallic supporting block 26 which isconnected to the positive side of the rectified picture signals, and theconnection of the stylus 25 which coacts with the mercury oxide coating,to the negative side of the picture signals. This method of connectionof the signals prevents smudging of the picture for the followingreasons:

The carbon particles which result from the stylus movement over therecord sheet and breakdown of the surface thereof are caused to remainat the surface instead of being attracted to the coating, it is to beunderstood that other electro-' lytic-type of record sheets forelectrostatic breakdown by picture signals may be employed. Thus, forblack-white picture recording, a coating of barium iodide upon the whiterecord sheet will result in a black-white pict'ure reproduction if therecord sheet is passed through the scanner mechanism herein described ina damp or slightly wet condition. With the carbon content paper I haveemployed successful operation using picture signals of the order of 400volts a erage intensity and operated at 100 lines per inchat a rate ofone inch per minute to produce half-tone effects of good quality.

I claim:

1. In a facsimile system operable on a continuous record sheet: a stylusarranged to continu-- ously contact the record sheet; means for oscil- 4tact the record sheet; means for oscillating said scanner, and means forholding the record sheet in a position substantially perpendicular tothe oscillation path of said scanner and curved in an are about saidscanner with a radius substantially that described by the scannerwhereby the record sheet coacts with the oscillated contacting scannerin a substantially linear marking in an oscillating means; and a springon said arm between said scanner and oscillating means for adjusting therelationship between said scanner and said sheet.

3. In a facsimile system operable on a continuous record sheet: a stylusarranged to continuously contact the record sheet; means for oscillatingsaid contacting stylus across said sheet comprising a scanner armattached to said stylus; and means for holding the record sheet in aposition substantially perpendicular to all positions of said stylus andcurved in an are about said stylus with a radius substantially thatdescribed by the stylus, said stylus being arranged to mark the insidearced surface of the sheet, whereby the record sheet coacts with theoscillated contacting stylus in a substantiallyaperpendicular relationand in a straight line marking path on the sheet to compose a facsimileof the transmitted image, said scanner arm being slidably mounted on anoscillating member, said arm being slidable in a plane substantiallyperpendicular to that of the sheet; and means on said scanner armbetween said stylus and said oscillating member for regulating thepressure of said stylus against said sheet.

WILLIAM G. H. FINCH.

